No abstract

Papillary craniopharyngiomas (PCPs) are characterized by the presence of BRAF V600E mutations, which are emerging as a useful guide for diagnosis and treatment decision making. The ongoing multicenter phase 2 Alliance A071601 trial is evaluating the efficacy of BRAF and mitogen‐activated protein kinase kinase (MEK) inhibitors for patients with PCPs. With continued successful responses, it is proposed that BRAF (and MEK) inhibitors be evaluated for the neoadjuvant treatment of patients with PCPs.

SUMMARY Environmental cues provoke rapid transitions in gene expression to support growth and cellular plasticity through incompletely understood mechanisms. Lin28 RNA-binding proteins have evolutionarily conserved roles in post-transcriptional coordination of pro-growth gene expression, but signaling pathways allowing trophic stimuli to induce Lin28 have remained uncharacterized. We find that Lin28a protein exhibits rapid basal turnover in neurons and that mitogen-activated protein kinase (MAPK)-dependent phosphorylation of the RNA-silencing factor HIV TAR-RNA-binding protein (TRBP) promotes binding and stabilization of Lin28a, but not Lin28b, with an accompanying reduction in Lin28-regulated miRNAs, downstream of brain-derived neurotrophic factor (BDNF). Binding of Lin28a to TRBP in vitro is also enhanced by phospho-mimic TRBP. Further, phospho-TRBP recapitulates BDNF-induced neuronal dendritic spine growth in a Lin28a-dependent manner. Finally, we demonstrate MAPK-dependent TRBP and Lin28a induction, with physiological function in growth and survival, downstream of diverse growth factors in multiple primary cell types, supporting a broad role for this pathway in trophic responses.